Xerocomellus amylosporus

Features include 1) a dry, velvety cap that is dark olive-brown to grayish brown or vinaceous brown with whitish to yellow or pinkish flesh showing in the cracks, 2) flesh that may turn blue erratically and shows red in stem and around larval tunnels, 3) yellow pores that sometimes have reddish tints and that turn blue when bruised, 4) stem that is reddish or with red striations over a yellow base, some becoming brownish, olive-gray, reddish, or reddish brown, often with a red band at the top, 5) growth under conifers, alder or oak, and 6) microscopic characters that include weakly to distinctly amyloid spores, most with a truncate apex. |Siegel(2) say (in the California context), "There are three species that have been lumped under the incorrectly applied name X. chrysenteron, with X. diffractus being the most common and widespread of the bunch. X. amylosporus typically has a darker cap with more scattered and irregular cracks, the pores bruise dark inky blue, the stipe develops dingy brownish tones, and the spores are more reddish brown in color." X. salicicola is similar but much rarer, and "can be told apart by its more-often cracked cap and growth with willow", (Siegel(2) with Latin names italicized). |X. amylosporus is uncommon, but rather widespread, (Frank(9)). |Collections in dry habitats tend to form gastroid fruiting bodies, "and many Sierra Nevada collections are deformed", (Frank(9)). |The ITS sequence of the type of Gastroboletus xerocomoides is identical to that of the type of Xerocomellus amylosporus. Note that while about half of the spores of Gastroboletus xerocomoides were truncate as in X. amylosporus, the spores were described as inamyloid and wider, measuring 12.8-18(21) x 6.4-8 microns.